Nope.
If he had uranium, it was likely uranium-238 which doesn't work for nuclear weaponry. To create a nuclear weapon, he would have needed lots of specialized and expensive equipment to create uranium-235 which can be used for nuclear weaponry. Creating uranium-235 at home would be almost impossible.
Uranium-238 is not very radioactive and only emits alpha particles which can be easily stopped by human skin. By itself, it's not dangerous.
Also, nuclear terrorism has never even happened and I doubt this man has any knowledge that would help him commit mass murder with a nuclear weapon.
Lastly, US citizens are legally allowed to own uranium-238 since it is not dangerous unless someone has specialized equipment and training.